Roller guide



April 1963 w. E. THOMAS 3,087,665

ROLLER GUIDE Filed June 28, 1961 TIE-4:

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3,087,665 ROLLER GUIDE William E. Thomas, 1717 Laurel St., San Carlos, Calif. Filed June 28, 1961, Ser. No. 120,410 Claims. (Cl. 226-190) The present invention relates to a guide for handling a moving strip of pliable material and, more particularly, to a roller guide for guiding such strip precisely and substantially without friction along a path of travel.

In the art of handling strips of moving pliable material, the practice has been to use freely rotating rollers or fixed posts as guides along the path thereof. With the roller extreme accuracy of alignment is required, otherwise the strip of material tends to move laterally across the surface of the roller thereby causing alignment errors at subsequent positions along the path. To minimize such effects flanges are provided at the respective ends of the roller and as the strip moves laterally across the roller, a high pressure builds up between the edge of the strip and the flange. The pressure then becomes sufficient to slide the strip in the opposite direction on the roller toward realignment with inherent friction and wear.

With the fixed type of guide the eifective friction coefficient in a lateral direction is substantially zero and little force is required by a flange to realign the strip material. Since the guide does not rotates, it is apparent that there is considerable wear of the strip as it slides across the guide and that considerable additional forces are required to move the strip and overcome the resultant friction between the strip and guide.

It is therefore an object of the present invention to provide a new and improved guide for strip material as it is transported in a direction parallel to its length.

Another object of the invention is to provide a roller guide for strip material that minimizes the effect of contact between an edge of the strip and a flange of the guide.

Still another object of the invention is to provide a roller guide for strip material whereby precise alignment of the guide is not required.

A further object of the invention is to provide a roller guide for strip material whereby friction between the roller and strip is minimized during transport of the strip along a precise path of travel.

According to the present invention a roller guide is mounted along the path of a strip of pliable material. The guide is provided with a plurality of spring-mounted segments, each segment being separately moveable in an axial direction between flanges of the roller guide. The collective surfaces of the segments present a substantially cylindrical surface to the strip during movement thereof and are arranged so that only two of the segments contact the strip at a time with each segment having a period free of contact with the strip. Now, if the strip approaches the roller guide at an angle, or if the roller guide is not precisely aligned perpendicular to the path of the strip, an edge of strip bears against the adjacent flange. Pressure between the strip and flange builds up and forces the strip laterally away from the flange. Because the segments are free to move axially in the same direction as the lateral force exerted on the strip by the flange, the strip and segment both move. Thus, relative movement in a lateral direction between the strip and the guide is minimized. During the period a segment is not in contact with the strip the spring returns the segment to its original position. The effect of such action prevents cumulative forces between the strip and flange.

Other objects and advantages of the present invention will be readily apparent from the. following description and claims considered together with the accompanying drawing, in which:

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FIGURE 1 is a perspective view of a roller guide in accordance with the present invention;

FIGURE 2 is a cross-sectional View, in elevation, of the guide of FIGURE *1;

FIGURE 3 is a cross-sectional view of the invention as taken along the lines 3-3 of FIGURE 2; and

FIGURE 4 is a characteristic diagram illustrating operation of the invention.

Referring to FIGURE 1 of the drawing, a roller guide 11 is suitably mounted as part of a transport system (not shown) for a strip for pliable material, such as magnetic tape 12, which is being moved under tension along a path substantially parallel to its length. As illustrated, the roller 11 has a substantially cylindrical surface 13 in contact with the tape 12 and the surface is provided by separately mounted segments 15 and 16, as will be further described hereinafter. While the number of surface segments has been shown as two in number, and will be described with respect to such number, a greater number may be readily used to further improve the results obtained with the invention.

To suitably mount the roller guide 11 a stud 21 having a flat portion 22 (see FIGURE 2) at one end is inserted into a matching opening of a suitable support plate (not shown) and in such manner the stud 21 is prevented from rotating. A spool 23 having a central portion 24 and two end flanges 26 and 27 is provided with an axial bore 28 so that the spool may be rotatably mounted on the extended portion of the stud 21. Outer races of ball bearing assemblies 31 and 32 are press fitted into suitable recesses in the respective ends of the spool 23 at the bore 28 with inner races engaging the stud 2-1. The spool 23 is thereby mounted for substantially frictionless rotation about the stud 21.

For proper positioning of the spool 23 on the stud 21 a lower collar 33 is secured to the stud 21, as by a set screw 34, and is engaged against a flange 36 that extends stud 21 and supports the inner race of bearing 32. Collar 33 has an outer flange 37 extending toward, but not touching, the flange 27 of the spool 23. Thus, there is provided a recess 38 between the collar 33 and the flange 27, the purpose of which will be set forth hereinafter. The upper end of the spool 23 is secured in position by an upper collar 39*, generally similar to the lower collar 33, and differing mainly in that a screw 40* is extended centrally through the upper collar into a suitably threaded axial opening of the stud 21. Upper collar 39 also has an inner flange 36a supporting the inner race of bearing 31.

In addition to being the basic rotating element of the guide 11, the spool 23 also carries the tape contacting segments 15 and 16. Each of the segments 15 and 16 has an axial length less than the distance between the two flanges 26 and 27 of the spool 23 and are contoured to be less than a half circle for the embodiment illustrated in the drawing. Both of the segments 15 and 16 are mounted in the same manner at each end thereof and for simr plicity of explanation only the mounting structure at one end will be described. A pair of spaced-apart pins 41 are mounted on the end of the segment 16 and extended in an axial direction through respective openings 42 in the adjacent flange 26 into the recess 38. The extended end of each pin 41 is provided with a portion 43 of reduced diameter upon which is mounted a leaf spring 44 having suitable openings at the respective ends thereof. To secure the spring 44 press fitted washers 46, or other suitable fasteners, are used. So that the segment 16 is spring-loaded with respect to the spool 23, at least one pin 47, two being illustrated by way of example, is extended from the flange 26 into the recess 38 through a suitable opening in the spring 44. Each pin 47 has a necked-down portion 48 mounting the spring 44, and a press fitted Washer 49 secures thespring on the pin. Thus, with both ends of the segment 16 spring-mounted in the foregoing manner the segment is held in a position midway between the two flanges 26 and 27. In accordance with the invention the strength of the springs 44 is selected to provide minimum resistance to any axial movement of the segments, but sufiicient to return the segment to the position midway between the flanges 26 and 27.

In addition to the structural details described in the foregoing, some of the elements may be advantageously detailed in a further manner. Thus, the flanges 26 and 27 may be provided with the opposing inner faces diverging outward at a slight angle to present no sharp corners to the tape 12, even if the tape approaches the guide at an angle. Also, the recess 38 may be packed with an energy absorbing material (not shown), such as felt, to damp out possible oscillations that might occur at certain resonant speeds of rotation and overshoots that might occur when the segments are returned to a central position by springaction. For some applications it may be desired to adjust the axial position of the guide 11 on the stud 21, and to permit such adjustment matching threads may be provided on engaging portions of the collars 33 and 39 of the spool 23 and the stud 21. While the tape engaging surfaces of the segments 15' and 16 have been shown as cylindrical in contour, the surfaces may readily have crown face, valley face, or other configurations.

Now consider the operation of the present invention with a tape 12 engaging the surface of the guide 11 for an angle less than the angular span of one of the segments. Thus, for the two-segment guide of FIGURE 1 the tape 12 is wrapped about the surface thereof for less than 180- degrees of the circumference. When the alignment of the guide 11 is precisely perpendicular to the path of the tape 12 and the tape approaches the guide with no angular deviation, the guide operates in the same manner as the prior art roller guide to guide the tape along its path with minimum friction. Should either of the foregoing factors vary, the tape contacts one of the flanges 15 or 16 dependent upon which direction the deviation occurs. The normal action of a roller when tape is angularly dravm thereacross is to continue the lateral movement of the tape; however, the presence of a flange inhibits such action by establishing a force component in the opposite direction. With the spring-mounted segments 15 and 16 of the invention, the lateral force component resulting from pressure between the tape 12 and the flange 26 or 27 is absorbed by the springs 44 during movement of the respective segments. It will be readily apparent that the movement of the segments 15, 16 along with the tape 12, instead of the tape laterally sliding across the surface of the guide, reduces the frictional forces by a considerable amount.

For a better understanding of the foregoing reference is made to FIGURE 4, which illustrates a characteristic curve for operation of the invention with the indicated degree point corresponding to a ninety-degree Wrap of the tape and the positioning of the boundary between segments 15-16 at the leading end of the wrapped length of tape. Lateral pressure between the tape 12 and the respective flange 26, 27 at such defined point is at a certain value 50 and increases at a rate, indicated by the slope of line 51, until the second segment contacts the tape. The addition of two more springs 44 to resist movement of the tape 12 laterally causes the rate 'of increase of pressure to double, as shown by line 52, during the succeeding 90-degrees of rotation of the guide 11. As soon as the 180-degree point is reached in rotation from the defined starting point, only one segment 15, 16 is involved and the pressure drops back to a value corresponding to the pressure value 50. Thereafter the pressure varies in a similar manner during continued rotation of the guide 11. It will be readily apparent from the foregoing that, since the value of pressure returns periodically to the same value, the pressure between the tape 12 and 4 respective flange 26, 27 does become accumulative as with prior art roller guides.

While the salient features of the present invention have been set forth with respect to certain details, particularly with respect to the number of segments, it should be realized that a greater number of segments and a lesser degree of tape wrap would reduce the pressures involved, on an average basis, for a complete revolution of the roller guide of the present invention. Also, it will be readily apparent that other structural combinations are possible for mounting the segments to provide axial movement thereof. For example, the springs could be mounted at only one end of the device. Also, helical instead of leaf springs could be used; and, in place of the guide pins 41, the segments could be mounted on linear (axiallyaligned) anti-friction ball bearings. Also, in certain ap plications wherein the roller is to be mounted with the axis vertical, the springs could be eliminated altogether and the segments returned to starting position by the action of gravity alone. Such an arrangement would double the excursion of the segments. Furthermore, in certain applications the flanges may be omitted altogether. It will therefore be apparent that numerous modifications and changes may be made within the spirit and scope of the invention and it is not intended to limit the invention to the exact details shown and described except as defined in the following claims.

What is claimed is:

1. A roller guide for strip material, comprising: a plurality of strip engaging members arranged about a common axis and presenting a substantially 36'O-degree strip-engaging surface; and means for mounting and guiding said members for rotary motion about said axis and for axial motion with respect to one another and to said axis, said means permitting resultant motion of each member in any of a plurality of planes including a plane perpendicular to said axis, whereby strip material passing over any of said members at any angle to said axis urges said member to follow said strip in said axial motion and thereby to support said strip without axial slippage.

2. A roller guide for strip material, comprising: a plurality of strip engaging members arranged about a common axis and presenting a substantially 360-degree strip engaging surface; means for mounting and guiding said members for rotary motion about said axis and for axial motion with respect to one another and to said axis; said means permitting resultant motion of each member in any of a plurality of planes including a plane perpendicular to said axis, and means mounted at at least one end of said members and extending beyond the periphery of said surface for guiding the edge of said strip material, Whereby said strip passing over any of said members at any angle to said axis urges said member to follow said strip in said axial motion and thereby to support said strip without axial slippage.

3. A roller guide for strip material, comprising: a plurality of strip engaging members arranged about a common axis and presenting a substantially 360-degree stripengaging surface; means for mounting and guiding said members for rotary mot-ion about said axis and for axial motion with respect to one another and to said axis? said means permitting resultant motion of each member in any of a plurality of planes including a plane perpendicular to said axis, and a pair of flanges mounted at either end of said members and extending beyond the periphery of said surface for guiding the edges of said strip material, said flanges being spaced apart for a distance substantially greater than the length of said members to permit said axial motion of said members, whereby strip material passing over any of said members at any angle to said axis urges said member to follow said strip in said axial motion and thereby to support said strip without axial slippage.

4. A roller guide for strip material, comprising: a plurality of strip engaging members arranged about a common axis and presenting a substantially 360-degree stripengaging surface; means for mounting and guiding said members for rotary motion about said axis and for axial motion with respect to one another and to said axis; said means permitting resultant motion of each member in any of a plurality of planes including a plane perpendicular to said axis, and a pair of flanges mounted at either end of said members for rotation therewith and extending beyond the periphery of said surface for guiding the edges of said strip material, said flanges being spaced apart for a distance substantially greater than the length of said members to permit said axial motion of said members, whereby strip material passing over any of said members at any angle to said axis urges and member to follow said strip in said axial motion and thereby to support said strip without axial slippage.

5. A roller guide for strip material, comprising: a plurality of strip engaging members arranged about a common axis and presenting a substantially 360-degree strip-engaging surface; and means for mounting and guiding said member for rotary motion about said axis and for axial motion with respect to one another and to said axis; said means permitting resultant motion of each member in any of a plurality of planes including a plane perpendicular to said axis, said last-named means including means for urging said members to a neutral axial position, whereby strip material passing over any of said members at any angle to said axis urges said member to follow said strip in said axial motion and thereby to support said strip without axial slippage.

6. A roller guide for strip material, comprising: a plurality of strip engaging members arranged about a common axis and presenting a substantially 350-degree stripengaging surface; and means for mounting and guiding said members for rotary motion about said axis and for axial motion with respect to one another and to said axis; said means permitting resultant motion of each member in any of a plurality of planes including a plane perpendicular to .said axis, said last-named means including spring means mounted at at least one end of and engaging said members and urging said members to a neutral axial position.

7. A roller guide for strip material, comprising: a plurality of strip engaging members arranged about a cornrnon axis and presenting a substantially 360- degree stripe-ngaging surface; means for mounting and guiding said members for rotary motion about said axis and for axial motion with respect to one another and to said axis; said means permitting resultant motion of each member in any of a plurality of planes including a plane perpendicular to said axis; and a pair of flanges mounted at either end of said members for rotation therewith and extending beyond the periphery of said surface for guiding the edges of said strip, said flanges being spaced apart for a distance substantially greater than the length of said members to permit said axial motion of said members; said mounting and guiding means including spring means mounted between said flanges and said members and urging said members to a neutral axial position, whereby strip material passing over any of said members at any angle to said axis urges said member to follow said strip in said axial motion and thereby to support said strip without axial slippage.

8. In combination with a tape, a roller guide comprising: a plurality of tape engaging members arranged about a common axis and presenting a substantially 360- degree tape-engaging surface, and means for mounting and guiding said members for rotary motion about said axis and for axial motion with respect to one another and to said axis, said means permitting resultant motion of each member in any of a plurality of planes including a plane perpendicular to said axis, said tape being wrapped part way around said guide and engaging at least one of said members, with the angle of wrap of said tape being less than the angle subtending all of said members save one, whereby tape passing over any of said members at any angle to said axis urges said member to follow said tape in said axial motion and thereby to support said tape without axial slippage, and whereby each of said members in each rotation thereof is freed from engagement with said tape for reverse axial motion.

9. In combination with a tape, a roller guide comprising: a plurality of tape engaging members arranged about a common axis and presenting a substantially 360-degree tape-engaging surface, means for mounting and" guiding said members for rotary motion about said axis and for axial motion with respect to one another and to said axis; said means permitting resultant motion of each member in any of a plurality of planes including a plane perpendicular to said axis, said tape being wrapped part way around said guide and engaging at least one of said members, with the angle of wrap of said tape being less than the angle subtending all of said members save one, a pair of flanges mounted at either end of said members for rotation therewith and extending beyond the periphery of said surface for guiding the edges of said tape, said flanges being spaced apart for a distance substantially greater than the length of said members to permit said axial motion of said members; said mounting and guiding means including spring means mounted between said flanges and said members and urging said members to a neutral axial position, whereby tape passing over any of said members at any angle to said axis urges said member to follow said tape in said axial motion and thereby to support said tape without axial slippage, and whereby each of said members in each rotation thereof is freed from engagement with said tape for reverse axial motion.

10. In combination with a tape, a roller guide comprising: a central shaft mounted for free axial rotation; a pair of substantially semi-cylindrical tape engaging members, means for mounitng and guiding said members on said shaft for rotation therewith and for presenting a substantially 360-degree tape-engaging surface coaxial with said shaft, said tape being wrapped part way around said guide and engaging at least one of said members, with the angle of wrap of said tape being less than degrees, said means also mounting and guiding said members for axial sliding motion on said shaft; said means permitting resultant motion of each member in any of a plurality of planes including a plane perpendicular to axis, a pair of flanges mounted at either end of said shaft for rotation therewith and extending beyond the periphery of said surface for guiding the edges of said tape, said flanges being spaced apart for a distance substantially greater than the length of said members to permit said axial motion of said members; said mounting and guiding means including means mounted between said flanges and said members for urging said members to a neutral axial position, whereby tape passing over any of said members at any angle to said axis urges said member to follow said tape in said axial motion and thereby to support said tape without axial slippage, and whereby each of said members in each rotation thereof is freed from engagement with said tape for reverse axial motion.

References Cited in the file of this patent UNITED STATES PATENTS 678,121 Lewis July 9, 2,998,906 Vice et al Sept. 5, 1961 3,052,395 Scott Sept. 4, 1962 

6. A ROLLER GUIDE FOR STRIP MATERIAL, COMPRISING: A PLURALITY OF STRIP ENGAGING MEMBERS ARRANGED ABOUT A COMMON AXIS AND PRESENTING A SUBSTANTIALLY 350-DEGREE STRIPENGAGING SURFACE; AND MEANS FOR MOUNTING AND GUIDING SAID MEMBERS FOR ROTARY MOTION ABOUT SAID AXIS AND FOR AXIAL MOTION WITH RESPECT TO ONE ANOTHER AND TO SAID AXIS; SAID MEANS PERMITTING RESULTANT MOTION OF EACH MEMBER IN ANY OF A PLURALITY OF PLANES INCLUDING A PLANE PERPENDICULAR TO SAID AXIS, SAID LAST-NAMED MEANS INCLUDING SPRING MEANS MOUNTED AT AT LEAST ONE END OF AND ENGAGING SAID MEMBERS AND URGING SAID MEMBERS TO A NEUTRAL AXIAL POSITION. 